1. Field of the Disclosure
This disclosure relates to a liquid crystal display device, and more particularly to an array substrate for a liquid crystal display device and a manufacturing method thereof, which is adaptive for improve the picture quality by minimizing photo leakage current, and a liquid crystal display device having the same.
2. Description of the Related Art
In general, a liquid crystal display device controls the light transmittance of liquid crystal by use of electric field, thereby displaying a picture. To this end, the liquid crystal display device includes a liquid crystal display panel where pixel areas are arranged in a matrix shape, a drive circuit for driving the liquid crystal display panel, and a backlight unit for supplying a designated amount of light to the liquid crystal display panel.
In the liquid crystal display panel, a plurality of gate lines and a plurality of date lines are arranged to cross, and a pixel area is located in an area which is defined by the perpendicular intersection of the gate lines and the date lines. A common electrode and pixel electrodes for applying electric field to each of the pixel areas are formed in the liquid crystal display panel. Each of the pixel electrodes is connected to the data line through a source terminal and a drain terminal of a thin film transistor that is a switching device. The thin film transistor is turned on by a scan pulse applied to the gate line to make a data signal of the data line charged in the pixel electrode.
The liquid crystal display panel includes two substrates (upper and lower substrates) and a liquid crystal layer formed between the two substrates. A color filter and a black matrix are formed in the upper substrate of the two substrates, and a thin film transistor (TFT) is formed in the lower substrate to correspond to the black matrix.
The light exited from the light source of the backlight unit is reflected by the liquid crystal cells forming a liquid crystal layer, the black matrix and the color filter of the upper substrate of the liquid crystal display panel, thereby affecting a channel layer of the thin film transistors. Hereby, a pixel voltage charged in the pixel electrode is affected to generate a difference between the pixel electrode charged in the pixel electrode and the actual data signal supplied to the data line, thereby generating a picture quality deterioration problem, e.g., a picture which is not wanted is displayed.
The channel layer of the thin film transistor is affected by light, thus a leakage current is generated in the channel layer if the light reflected by the liquid crystal cell, the black matrix and the color filter of the upper substrate enters into the channel layer of the thin film transistor. Because of this, the pixel voltage charged in the pixel electrode is affected, thereby generating a picture quality deterioration, e.g., patterns which are not wanted are generated.